Felix revisits the Raspberry Pi no HDMI project. There were quite a few questions on the community regarding the GPIO connections between the Raspberry Pi and the TFT along with the button matrix. The github repository for this project includes the bill of material, data sheets, enclosure, OS setup, and schematics. In there you can find the GPIO set up, along with a spreadsheet for the GPIO connections, under the OS set up. A good reference for this can be found at www.raspberrypi.org/documentation/hardware/raspberrypi/dpi/README.md. There you can find a chart that shows the different modes that can output the display through the GPIO.

They are using the 565 configuration for the TFT display. It opens up GPIO 27 to 20 for the button matrix. The connections they go with for the TFT screen are GPIO 27, 22, 26, 23, 24, 25, 20, and 21. Finally, Felix shows you where to look for the connections on the Raspberry Pi itself.